JP2021099935A - Fuel cell system - Google Patents

Abstract

To provide a fuel cell system that can easily discharge liquid water remaining in an ejector after a fuel cell is warmed up.SOLUTION: A fuel cell system includes a fuel cell equipped with reaction gas inlet and outlet, a first injection device that intermittently injects reaction gas, second and third injection devices that continuously inject the reaction gas, an ejector equipped with the first or second injection device and a discharge port for reaction gas from the outlet, a first flow path connecting the inlet and the discharge port, a second flow path that guides the reaction gas of the third injection device to the first flow path without going through the ejector, and a control device that controls the first to third injection devices. The ejector includes a common third flow path for flowing the reaction gas from the outlet and the first and second injection devices to the discharge port. The control device warms up by executing the injection of the third injection device, suppress the backflow of the reaction gas from the third injection device to the ejector by executing the injection of the second injection device, and execute the injection of the first injection device after the warm-up operation is completed.SELECTED DRAWING: Figure 1

Description

The present invention relates to a fuel cell system.

For example, in the vicinity of the off-gas outlet of a fuel cell stack that has stopped operation in a sub-zero environment, the water generated by power generation may freeze and become ice to block the off-gas outlet. Therefore, when the fuel cell system is restarted, a warm-up operation is performed in which the ice is melted by the heat generated by the power generation in order to suppress the deterioration of the power generation performance due to the blockage of the off-gas outlet.

However, in a fuel cell system including an off-gas circulation path and an ejector, not only hydrogen gas is supplied from the tank to the fuel cell stack via the ejector, but also off-gas is supplied from the circulation path via the ejector. (See, for example, Patent Document 1), other gases such as nitrogen in the off-gas remaining in the circulation path and the ejector (hereinafter referred to as “impurity gas”) are mixed with the hydrogen gas to reduce the concentration of the hydrogen gas. For this reason, since the off-gas outlet is blocked in the fuel cell stack, the amount of hydrogen gas supplied may be insufficient due to the filling of impurity gas, and power generation may not be continued until the ice is sufficiently melted. ..

Japanese Unexamined Patent Publication No. 2013-134882

On the other hand, if the linear solenoid valve connected to the tank bypasses the ejector and continuously supplies high-concentration hydrogen gas to the fuel cell, power generation can be continued. However, when hydrogen gas is supplied via a route that bypasses the ejector, the pressure in the circulation path from the off-gas outlet to the ejector is lower than the pressure in the fuel cell stack, so the hydrogen gas flows back into the ejector and hydrogen. The gas supply may decrease.

Therefore, another ejector connected in parallel to the above ejector (hereinafter referred to as "additional ejector") and another linear solenoid valve connected to the additional ejector (hereinafter referred to as "additional valve") are added. However, it is conceivable to suppress the backflow by flowing a small amount of hydrogen gas from the additional valve through the additional ejector. However, since the hydrogen gas flowing from the additional valve does not pulsate the pressure of the anode system, it is difficult for the liquid water sucked into the additional ejector together with the off-gas or the liquid water generated by the dew condensation of water vapor due to the low temperature hydrogen gas to be discharged from the additional ejector. , It remains in the additional ejector even after warm-up operation, and if the outside temperature falls below the freezing point, it may freeze and interfere with the injection of hydrogen gas.

Therefore, the present invention has been made in view of the above problems, and an object of the present invention is to provide a fuel cell system capable of easily discharging the liquid water remaining in the ejector after the fuel cell has been warmed up.

The fuel cell system of the present invention includes a fuel cell provided with an inlet and an outlet for a reaction gas used for power generation, a first injection device for intermittently injecting the reaction gas, and a first injection device for continuously injecting the reaction gas. An ejector including two injection devices and a third injection device, a discharge port for discharging the reaction gas discharged from the discharge port together with the reaction gas injected from the first injection device or the second injection device, and an ejector. A first flow path connecting the introduction port and the discharge port, a second flow path that guides the reaction gas injected from the third injection device to the first flow path without passing through the ejector, and the above. It has a first injection device, the second injection device, and a control device that controls the injection of the third injection device, and the ejector is the reaction gas discharged from the discharge port and the first injection device. A common third flow path for flowing the reaction gas injected from the second injection device to the discharge port is provided, and the control device warms the fuel cell by executing injection of the third injection device. The reaction from the third injection device to the third flow path from the discharge port via the second flow path and the first flow path by performing the machine operation and executing the injection of the second injection device. After the backflow of gas is suppressed and the warm-up operation of the fuel cell is completed, the injection of the first injection device is executed.

According to the above configuration, the control device warms up the fuel cell by executing the injection of the third injection device, and the second flow path from the third injection device by executing the injection of the second injection device. And the backflow of the reaction gas from the discharge port to the third flow path through the first flow path is suppressed. Since the second injection device and the third injection device continuously inject the reaction gas, the backflow of the reaction gas to the ejector is suppressed, and the fuel cell from the third injection device has a high concentration that does not contain the impurity gas in the ejector. Warm-up operation can be performed by continuously supplying the reaction gas of.

Further, the control device executes the injection of the first injection device after the warm-up operation of the fuel cell is completed. Since the first injection device injects the reaction gas intermittently and the fuel cell uses the reaction gas for power generation, the pressure in the ejector pulsates due to the intermittent injection of the first injection device.

Further, the ejector includes a common third flow path for flowing the reaction gas discharged from the discharge port and the reaction gas injected from the first injection device and the second injection device to the discharge port. Therefore, the liquid water generated in the third flow path by the injection of the second injection device is discharged from the discharge port by the pulsation of the pressure due to the intermittent injection of the first injection device.

Therefore, the fuel cell system of the present invention can easily discharge the liquid water remaining in the ejector after the fuel cell is warmed up.

In the above configuration, the control device may stop the injection of the second injection device and the third injection device after the warm-up operation of the fuel cell is completed.

In the above configuration, the control device may stop the injection of the first injection device until the warm-up operation of the fuel cell is completed.

In the above configuration, the control device may execute the injection of the second injection device at a flow rate corresponding to the temperature of the fuel cell at the start of the warm-up operation of the fuel cell.

In the above configuration, the ejector has a first nozzle that injects the reaction gas injected from the first injection device into the third flow path, and the reaction gas injected from the second injection device. A second nozzle for injecting into the three flow paths may be provided.

In the above configuration, the ejector has a common third nozzle that injects the reaction gas injected from the first injection device and the reaction gas injected from the second injection device into the third flow path. You may have.

In the above configuration, the control device may warm up the fuel cell until the temperature of the fuel cell exceeds the freezing point.

In the above configuration, the first injection device may include an injector, and the second injection device and the third injection device may include a linear solenoid valve.

According to the present invention, the liquid water remaining in the ejector after the warm-up operation of the fuel cell can be easily discharged.

It is a block diagram which shows an example of a fuel cell system. It is a figure which shows an example of the flow of the anode gas and the anode off-gas at the time of warm-up operation of a fuel cell. It is a figure which shows an example of the flow of the anode gas and the anode off gas at the time of a normal operation of a fuel cell. It is a figure which shows an example of the time change of the flow rate of the anode gas injected from a bypass linear solenoid valve, an auxiliary linear solenoid valve, and an injector. It is a figure which shows the performance comparison result of an injector and a linear solenoid valve. It is a flowchart which shows an example of the processing of an ECU (Electronic Control Unit). It is a block diagram which shows the example of another fuel cell system. It is a block diagram which shows the fuel cell system of the comparative example.

(Configuration of fuel cell system 100)
FIG. 1 is a configuration diagram showing an example of a fuel cell system 100. The fuel cell system 100 is mounted on, for example, a fuel cell vehicle and has a fuel cell (FC) 1, a motor M, a cathode system 2, an anode system 3, and a control system 7. It should be noted that the illustration of the electrical configuration for connecting the FC1 and the motor M is omitted.

FC1 includes a plurality of single cell laminates of a solid polymer electrolyte type. FC1 receives the supply of the cathode gas and the anode gas and generates electricity by the chemical reaction of the cathode gas and the anode gas. In this embodiment, air containing oxygen is used as the cathode gas, and hydrogen gas is used as the anode gas. The anode gas is an example of a reaction gas used for power generation. The electric power generated by FC1 is supplied to the motor M.

Further, FC1 has an inlet 11 and an outlet 12 for the anode gas, and an inlet 13 and an outlet 14 for the cathode gas. The inlet 11 and the outlet 12 of the anode gas are connected via the anode gas flow path L31, and the inlet 13 and the outlet 14 of the cathode gas are connected via the cathode gas flow path L21. The anode gas flow path L31 and the cathode gas flow path L21 include a manifold penetrating the laminated body of the single cell, a groove formed in the separator of the single cell, and the like. The inlet 11 and the outlet 12 of the anode gas are examples of the inlet and the outlet of the reaction gas, respectively.

The cathode system 2 supplies air containing oxygen as a cathode gas to FC1. For example, the cathode system 2 includes a cathode supply pipe L20, a cathode discharge pipe L22, and an air compressor 20.

The downstream end of the cathode supply pipe L20 is connected to the cathode gas inlet 13 of FC1. An air compressor (ACP) 20 is provided in the cathode supply pipe L20. The air compressor 20 compresses the cathode gas. The cathode gas flows through the cathode supply pipe L20 and is supplied to FC1 as indicated by the arrow R20. As shown by the arrow R21, the cathode gas in FC1 flows from the inlet 13 through the cathode gas flow path L21 and chemically reacts with the anode gas to be used for power generation.

The upstream end of the cathode discharge pipe L22 is connected to the outlet 14 of the cathode off gas of FC1. The FC1 discharges the cathode gas used for power generation as the cathode off gas from the outlet 14 to the cathode discharge pipe L22. The cathode off gas flows through the cathode discharge pipe L22 and is discharged to the outside as indicated by an arrow R22.

The anode system 3 supplies the anode gas to FC1. The anode system 3 includes an anode supply pipe L30, an anode discharge pipe L32, a return pipe L33, a bypass pipe L34, an exhaust drain pipe L35, a fuel tank 30, an injector (INJ) 31, an auxiliary linear solenoid valve (LS) 32, and a bypass linear solenoid. It includes a valve (bypass LS) 33, an ejector 4, a gas-liquid separator 5, and an anode discharge valve 6.

Anode gas is stored in the fuel tank 30 in a high pressure state. The fuel tank 30 supplies the anode gas to the INJ31, the auxiliary LS32, and the bypass LS33. INJ31 injects anode gas intermittently. For example, INJ31 injects anode gas at a predetermined flow rate at regular time intervals. The auxiliary LS32 and the bypass LS33 continuously inject the anode gas. Further, the auxiliary LS32 and the bypass LS33 can inject the anode gas at an arbitrary flow rate.

The bypass LS33 and the auxiliary LS32 inject the anode gas in the warm-up operation of FC1, and the INJ31 injects the anode gas in the normal operation after the warm-up operation of FC1. The INJ31 is an example of the first injection device, the auxiliary LS32 is an example of the second injection device, and the bypass LS33 is an example of the third injection device.

The INJ31 and the auxiliary LS32 are connected to the ejector 4. The bypass LS33 is connected to the anode supply pipe L30 via the bypass pipe L34.

FIG. 1 shows a cross section of the ejector 4 along the direction in which the anode gas flows. The ejector 4 has a plate-shaped fixing portion 40, a large-diameter nozzle 41, a small-diameter nozzle 42, and a diffuser 43. Examples of the material of the ejector 4 include, but are not limited to, SUS (Steel Use Stainless).

The fixing portion 40 fixes the large-diameter nozzle 41 and the small-diameter nozzle 42. The inlet 410 of the large diameter nozzle 41 is connected to INJ31, and the inlet 420 of the small diameter nozzle 42 is connected to the auxiliary LS32. The large-diameter nozzle 41 and the small-diameter nozzle 42 inject the anode gas from the INJ 31 and the auxiliary LS 32 from the injection port to the diffuser 43, respectively. The diameter of the injection port of the large-diameter nozzle 41 is larger than the diameter of the injection port of the small-diameter nozzle 42. The large-diameter nozzle 41 is an example of the first nozzle, and the small-diameter nozzle 42 is an example of the second nozzle.

The diffuser 43 includes an ejector flow path 44 through which the anode gas flows, and an outlet 46 connected to the anode supply pipe L30. Anode gas injected from the large-diameter nozzle 41 and the small-diameter nozzle 42 flows through the ejector flow path 44. The anode gas flows through the ejector flow path 44 and is discharged from the outlet 46 to the anode supply pipe L30.

Further, on the side surface of the diffuser 43, an inflow port 45 connected to the return pipe L33 is provided. The return pipe L33 connects the inflow port 45 and the gas-liquid separator 5. The anode off gas flowing from the gas-liquid separator 5 to the return pipe L33 is sucked into the ejector flow path 44 from the inflow port 45 by the anode gas injected from the large-diameter nozzle 41 or the small-diameter nozzle 42 acting as a driving fluid. .. Anode-off gas flows into the inflow port 45 from the gas-liquid separator 5.

The anode off-gas flows from the inflow port 45 through the ejector flow path 44, and is discharged together with the anode gas from the outflow port 46 to the anode supply pipe L30. The ejector flow path 44 is an example of a common third flow path for flowing the anode off gas and the reaction gas injected from INJ31 and the auxiliary LS32 to the outlet 46, and the anode off gas is an example of the reaction gas discharged from FC1. Is.

One end of the anode supply pipe L30 is connected to the outlet 46 of the ejector 4, and the other end of the anode supply pipe L30 is connected to the inlet 11 of the anode gas of FC1. The anode supply pipe L30 is an example of a first flow path connecting the inlet 11 and the inlet 45. Further, one end of the bypass pipe L34 extending from the bypass LS33 is connected in the middle of the anode supply pipe L30 (see reference numeral P). The bypass pipe L34 is an example of a second flow path that guides the anode gas injected from the bypass LS33 to the anode supply pipe L30 without passing through the ejector 4.

One end of the anode discharge pipe L32 is connected to the outlet 12 of the anode off gas of FC1, and the other end of the anode discharge pipe L32 is connected to the gas-liquid separator 5. The anode off-gas flows from the outlet 12 through the anode discharge pipe L32 and enters the gas-liquid separator 5.

The gas-liquid separator 5 separates liquid water from the anode off gas discharged from the outlet 12. One end of the exhaust drain pipe L35 is connected to the gas-liquid separator 5, and the other end of the exhaust drain pipe L35 is connected to the cathode discharge pipe L22. An anode discharge valve 6 is provided in the exhaust / drain pipe L35, and when the anode discharge valve 6 is opened, a part of the liquid water and the anode off-gas flowing out from the gas-liquid separator 5 is discharged / drain pipe as shown by an arrow R34. It flows to the cathode discharge pipe L22 via L35 and is discharged to the outside together with the cathode off gas.

One end of the return pipe L33 is connected to the gas-liquid separator 5, and the other end of the return pipe L33 is connected to the inflow port 45 of the ejector 4. The anode off gas flows from the gas-liquid separator 5 through the return pipe L33 and enters the inflow port 45 of the ejector 4.

The control system 7 includes an ECU 70, an ignition switch 71, an accelerator opening sensor 72, and a temperature sensor 73. The ignition switch 71 notifies the ECU 70 of an instruction to start and stop the fuel cell vehicle. The accelerator opening sensor 72 detects the opening degree of the accelerator (not shown) of the fuel cell vehicle and notifies the ECU 70. The temperature sensor 73 detects the temperature of the cooling water of FC1 and notifies the ECU 70. The ECU 70 processes the temperature measured by the temperature sensor 73 as the temperature of the FC1.

The ECU 70 includes a CPU (Central Processing Unit), a ROM (Read Only Memory), and a RAM (Random Access Memory). An ignition switch 71, an accelerator opening sensor 72, a temperature sensor 73, an air compressor 20, an INJ31, an auxiliary LS32, a bypass LS33, and an anode discharge valve 6 are electrically connected to the ECU 70. The ECU 70 controls the operation of the air compressor 20 and the injection of the INJ31, the auxiliary LS32, and the bypass LS33.

The ECU 70 starts power generation of FC1 when the ignition switch 71 is turned on, and stops power generation of FC1 when the ignition switch 71 is turned off. The ECU 70 operates the air compressor 20 when the ignition switch 71 is turned on. When the power generation of FC1 is started, the ECU 70 warms up the FC1 when the temperature of the FC1 is equal to or lower than the predetermined reference temperature TH, and then, when the temperature of the FC1 exceeds the predetermined reference temperature TH, the FC1 normally operates. Drive. The ECU 70 promotes heat generation and temperature rise of FC1 by lowering the stoichiometric ratio of the cathode gas in the warm-up operation as compared with the normal operation. Further, the ECU 70 may promote heat generation and temperature rise by stopping the operation of a cooling system (not shown) in the warm-up operation. In the following description, the supply of anode gas in warm-up operation and normal operation will be described.

(FC1 warm-up operation)
FIG. 2 is a diagram showing an example of the flow of the anode gas and the anode off gas during the warm-up operation of FC1. In FIG. 2, the same reference numerals are given to the configurations common to those in FIG. 1, and the description thereof will be omitted.

The ECU 70 warms up the FC1 by executing the injection of the bypass LS33. The anode gas injected from the bypass LS33 is introduced into the anode supply pipe L30 without passing through the ejector 4, as shown by the arrow R3. At this time, a part of the anode gas injected from the bypass LS33 flows back to the ejector 4 via the anode supply pipe L30 as indicated by the arrow R30r. The backflow of the anode gas goes from the outflow port 46 to the ejector flow path 44 via the bypass pipe L34 and the anode supply pipe L30.

On the other hand, the ECU 70 injects the anode gas into the auxiliary LS 32 so that the backflow of the anode gas from the bypass LS 33 is suppressed. The anode gas injected from the auxiliary LS 32 flows through the ejector flow path 44 as indicated by the arrow R2, and is discharged from the outlet 46 to the anode supply pipe L30.

Since the auxiliary LS32 and the bypass LS33 continuously inject the reaction gas, the backflow of the reaction gas to the ejector 4 is suppressed, and as shown by the arrow R30f, the bypass LS33 is sent to the FC1 via the anode supply pipe L30 to the ejector. Warm-up operation can be performed by continuously supplying a high-concentration reaction gas that does not contain the impurity gas in 4.

The ECU 70 injects the anode gas into the bypass LS 33 at a flow rate corresponding to the temperature of the temperature sensor 73, for example. Therefore, quick warm-up operation according to the temperature of FC1 is possible.

As shown by the arrow R31, the anode gas flows from the inlet 11 through the anode gas flow path L31 and chemically reacts with the cathode gas to be used for power generation. FC1 discharges the anode gas used for power generation as the anode off gas from the outlet 12 to the anode discharge pipe L32. The anode off-gas flows from the outlet 12 of FC1 through the anode discharge pipe L32 and enters the gas-liquid separator 5 as indicated by the arrow R32.

The anode off-gas flows from the gas-liquid separator 5 through the return pipe L33 and from the inflow port 45 of the ejector flow path 44 through the ejector flow path 44, as indicated by the arrow R33. That is, when the auxiliary LS 32 injects the anode gas, the anode off gas is sucked from the gas-liquid separator 5 into the ejector 4 via the return pipe L33. Since the anode off gas discharged from FC1 contains water generated by the power generation in FC1, the liquid water m that could not be separated by the gas-liquid separator 5 and the liquid water m in the ejector flow path 44 during the warm-up operation By cooling with a low-temperature anode gas, liquid water m is generated due to dew condensation of water vapor.

For example, if the liquid water m remains in the ejector flow path 44, the liquid water freezes below the freezing point to block the ejector flow path 44, and when the fuel cell system 100 is restarted, a sufficient flow of anode gas is supplied to the FC1. It may not be possible.

Therefore, in the normal operation after the completion of the warm-up operation, the ECU 70 discharges the liquid water remaining in the ejector flow path 44 by executing the injection of the INJ 31.

(Normal operation of FC1)
FIG. 3 is a diagram showing an example of the flow of the anode gas and the anode off gas during the normal operation of the FC1. In FIG. 3, the same reference numerals are given to the configurations common to those in FIG. 1, and the description thereof will be omitted.

The ECU 70 executes the injection of INJ31 after the warm-up operation of FC1 is completed. The anode gas injected from INJ31 flows through the ejector flow path 44 and is discharged from the outlet 46 to the anode supply pipe L30 as shown by the arrow R1. Further, the anode off gas in the return pipe L33 is sucked into the ejector flow path 44 from the inflow port 45, and discharged from the outflow port 46 to the anode supply pipe L30.

The anode gas and the anode off gas enter the anode gas flow path L31 of the FC1 from the anode supply pipe L30 via the inlet 11 as indicated by the arrow R30. Anode gas and part of anode off gas are used for power generation.

Since the INJ31 injects the anode gas intermittently and the FC1 uses the anode gas for power generation, the pressure in the ejector 4 pulsates due to the intermittent injection of the INJ31. The anode off gas sucked from the inflow port 45, the anode gas injected from the auxiliary LS 32, and the anode gas injected from INJ31 flow through the ejector flow path 44. Therefore, the liquid water m generated in the ejector flow path 44 by the injection of the auxiliary LS 32 is discharged from the outflow port 46 by the pulsation of the pressure due to the intermittent injection of the INJ 31.

The liquid water m in the ejector flow path 44 flows through the anode supply pipe L30, the anode gas flow path L31, and the anode discharge pipe L32, and is stored in the gas-liquid separator 5. The liquid water in the gas-liquid separator 5 is discharged from the cathode discharge pipe L22 when the anode discharge valve 6 is opened.

In the normal operation of the FC1, the ECU 70 calculates the current value required for the FC1 according to, for example, the accelerator opening degree detected by the accelerator opening degree sensor 72. The ECU 70 instructs the air compressor 20 to flow the cathode gas, and instructs the INJ 31 to flow the anode gas.

(Change in anode gas flow rate)
FIG. 4 is a diagram showing an example of a time change of the flow rate of the anode gas injected from the bypass LS33, the auxiliary LS32, and the INJ31. Reference numeral Ga indicates an example of a change in the anode gas flow rate of the bypass LS33 with respect to time, reference numeral Gb indicates an example of change in the anode gas flow rate of the auxiliary LS32 with respect to time, and reference numeral Gc indicates an example of change in the anode gas flow rate of INJ31 with respect to time. Is shown. Further, the reference numeral Gd indicates an example of a change in the temperature of FC1 with respect to time.

The ECU 70 warms up the FC1 during the period from the time 0 to the time Tc, and performs the normal operation of the FC1 after the time Tc. The ECU 70 switches the operation of the FC1 according to the temperature detected by the temperature sensor 73. As an example, the temperature of FC1 rises in proportion to time from the temperature Tm and exceeds the reference temperature TH at the time Tc.

During the warm-up operation, the ECU 70 executes the injection of the bypass LS33 at a flow rate Vd corresponding to the temperature Tm of the FC1 at time 0. As a result, the anode gas is supplied to the FC1 at an appropriate flow rate Vd, so that the temperature of the FC1 rises rapidly.

Further, the ECU 70 injects the auxiliary LS 32 at a flow rate Vr so that the backflow of the anode gas injected from the bypass LS 33 into the ejector flow path 44 is suppressed during the warm-up operation. The ECU 70 calculates an appropriate flow rate Vr from the flow rate Vd of the anode gas injected from the bypass LS33. The ECU 70 controls the anodic gas flow rate by setting the opening degree of the auxiliary LS32 and the bypass LS33.

Further, the ECU 70 stops the injection of INJ31 until the warm-up operation of FC1 is completed. Since the INJ 31 intermittently injects the anode gas, the pressure of the anode gas is pulsated to increase the circulation amount of the anode off gas sucked from the return pipe L33 into the ejector flow path 44. As the circulation amount of the anode off gas increases, the amount of liquid water generated in the ejector flow path 44 also increases. Therefore, the ECU 70 preferably stops the injection of the INJ31, but the injection is not limited to this, and the injection of the INJ31 may be executed at a flow rate sufficient to supplement the anode gas for suppressing the backflow.

When the temperature of FC1 exceeds the reference temperature TH, the ECU 70 executes normal operation of FC1 by executing injection of INJ31. Here, the reference temperature TH is 0 ° C. or higher, which is the freezing point. That is, the ECU 70 warms up until the temperature of FC1 exceeds the freezing point. As a result, freezing of the liquid water generated in the ejector flow path 44 during the warm-up operation is suppressed, so that it becomes easier to discharge the liquid water from the ejector flow path 44 by the injection of INJ31 than in the case of ice. ..

The ECU 70 intermittently injects the anode gas into the INJ 31 by turning the INJ 31 on and off, for example, in the cycle f. The ECU 70 determines the ON time Δt and the period f of the INJ31 according to the required current value of the FC1. Further, the flow rate Vn of the anode gas injected from INJ31 is constant.

When INJ31 injects the anode gas, the pressure of the anode gas rises due to the temporary rise in the amount of the anode gas in the anode system 3. However, since the anode gas is reduced by being used for power generation of FC1, the pressure of the anode gas is reduced immediately after the injection. Therefore, when the INJ 31 intermittently injects the anode gas, the pressure of the anode gas in the anode system 3 pulsates. At this time, since the pressure in the ejector flow path 44 also pulsates, the liquid water in the ejector flow path 44 is easily discharged from the outlet 46.

Further, since the responsiveness to the instruction of the ECU 70 is better in INJ31 than in the auxiliary LS32 and the bypass LS33, it is possible to more effectively discharge the liquid water by injecting the INJ31.

FIG. 5 is a diagram showing the performance comparison results of the injector and the linear solenoid valve. The solid line shows the performance of the injector (INJ31), and the dotted line shows the performance of the linear solenoid valve (auxiliary LS32 and bypass LS33). The injector is, for example, a solenoid valve, and the valve is opened and closed (opening is either 100% or 0%) by electrical on / off control. Unlike the injector, the linear solenoid valve enables the flow rate to be adjusted, so that it can be electrically controlled to an arbitrary opening degree (0 to 100%).

Reference numeral Ha indicates an example of a change in the flow rate of the anode gas with respect to time. The time Ts is the timing at which the ECU 70 instructs the injector and the linear solenoid valve to inject. The time required from the indicated time Ts to reach the maximum flow rate Vp is shorter for the injector than for the linear solenoid valve. That is, the responsiveness of the injector is better than that of the linear solenoid valve.

Reference numeral Hb indicates an example of change with respect to the time of the pressure difference Δp on the upstream side and the downstream side of the water droplet clogged in the flow path when the injector and the linear solenoid valve inject. Due to the above difference in responsiveness, the time required for the pressure difference Δp to reach the maximum values p1 and p2 is shorter for the injector than for the linear solenoid valve. Further, the maximum value p1 of the pressure difference Δp at the time of injection of the injector is larger than the maximum value p2 of the pressure difference Δp at the time of injection of the linear solenoid valve. Therefore, by executing the injection of INJ31, the ECU 70 discharges the liquid water more effectively than executing the injection of the auxiliary LS32 and the bypass LS33.

Referring to FIG. 4 again, the ECU 70 stops the injection of the auxiliary LS32 and the bypass LS33 in the normal operation after the warm-up operation is completed. Therefore, the consumption of the anode gas generated by the injection of the auxiliary LS32 and the bypass LS33 is suppressed. The ECU 70 may execute the injection of the auxiliary LS32 and the bypass LS33 in the normal operation when, for example, the required current value of the FC1 is large and it is predicted that the anode gas will be insufficient.

(Processing of ECU 70)
FIG. 6 is a flowchart showing an example of processing of the ECU 70. This process is executed in a state where the fuel cell system 100 has stopped operating due to the ignition switch 71 being turned off.

The ECU 70 determines whether or not the ignition switch 71 is turned on (step St1). When the ignition switch 71 is off (No in step St1), step St1 is executed again. When the ignition switch 71 is turned on (Yes in step St1), the ECU 70 operates the air compressor 20 to generate electricity in FC1 (step St2). As a result, the cathode gas starts to be supplied from the air compressor 20 to the FC1.

Next, the ECU 70 measures the temperature of the cooling water as the temperature of the FC1 by the temperature sensor 73 (step St3). When the temperature of FC1 is equal to or lower than the reference temperature TH (Yes in step St4), the ECU 70 warms up the FC1 (steps St5 to St8), and when the temperature of FC1 is higher than the reference temperature TH (No. in step St4). ), The normal operation of FC1 is performed (steps St11 to St13).

First, the warm-up operation will be described. The ECU 70 turns off INJ31 (step St5). Therefore, the anode gas is not supplied from INJ31 to FC1.

Next, the ECU 70 calculates the opening degree of the bypass LS33 based on the temperature of the FC1 (step St6). As a result, the ECU 70 determines the flow rate of the anode gas injected from the bypass LS33 according to the temperature of the FC1 at the start of the warm-up operation.

Next, the ECU 70 calculates the opening degree of the auxiliary LS32 based on the opening degree of the bypass LS33 so that the backflow of the anode gas from the bypass LS33 to the ejector flow path 44 is suppressed (step St7). For example, the ECU 70 calculates the opening degree of the auxiliary LS 32 so that the anode gas is injected at a flow rate that can cancel the backflow of the anode gas.

Next, the ECU 70 sets the opening degree of the bypass LS33 and the auxiliary LS32 (step St8). As a result, the bypass LS33 and the auxiliary LS32 start injecting the anode gas at a flow rate corresponding to the set opening degree (step St8). In this way, since the ECU 70 executes the injection of the bypass LS33 at a flow rate corresponding to the temperature of the FC1 at the start of the warm-up operation of the FC1, the temperature of the FC1 can be raised quickly.

Next, the ECU 70 measures the temperature of FC1 by the temperature sensor 73 (step St9). When the temperature of FC1 is equal to or lower than the reference temperature TH (No in step St10), the ECU 70 measures the temperature of FC1 again (step St9). When the temperature of FC1 is higher than the reference temperature TH (No in step St10), the ECU 70 performs normal operation of FC1 (steps St11 to St13).

Next, normal operation will be described. The ECU 70 closes the bypass LS33 and the auxiliary LS32 (step St11). As a result, the injection of the anode gas from the bypass LS33 and the auxiliary LS32 is stopped.

Next, the ECU 70 determines the required current value of the FC1 based on the detection value of the accelerator opening sensor 72, and calculates the ON time and the ON / OFF cycle (Δt and f in FIG. 4) of the INJ31 based on the required current value. (Step St12). Next, the ECU 70 controls INJ31 on / off according to the on time and the on / off cycle (step St13). As a result, the anode gas is supplied to FC1 at a flow rate corresponding to the required current value.

Next, the ECU 70 determines whether or not the ignition switch 71 is turned off (step St14). When the ignition switch 71 is turned on (No in step St14), each process after step St12 is executed again. When the ignition switch 71 is turned off (Yes in step St14), the INJ31 is turned off (step St15), and the air compressor 20 is stopped (step St16). As a result, the power generation of FC1 is stopped.

(Other fuel cell systems)
In the fuel cell system 100 described above, the ejector 4 has a separate large diameter nozzle 41 and a small diameter nozzle 42 connected to the INJ 31 and the auxiliary LS 32. That is, the ejector 4 includes a large-diameter nozzle 41 that injects the anode gas injected from the INJ 31 into the ejector flow path 44, and a small-diameter nozzle 42 that injects the anode gas injected from the auxiliary LS 32 into the ejector flow path 44. Therefore, the injection amount of the anode gas can be appropriately changed between the large-diameter nozzle 41 and the small-diameter nozzle 42. However, the INJ31 and the auxiliary LS32 are not limited to this, and may be connected to a common nozzle.

FIG. 7 is a configuration diagram showing an example of another fuel cell system 100a. In FIG. 7, the same reference numerals are given to the configurations common to those in FIG. 2, and the description thereof will be omitted.

The fuel cell system 100a has an ejector 4a provided with a single nozzle 41a instead of the ejector 4 described above. The INJ31 and the auxiliary LS32 are connected to the inlet 410a of the nozzle 41a via a bifurcated connecting pipe L4. Therefore, the anode gas injected from the INJ31 or the auxiliary LS32 flows from the nozzle 41a to the ejector flow path 44 as indicated by the arrow R4. The nozzle 41a is an example of the third nozzle.

As described above, the ejector has a common nozzle 41a that injects the anode gas injected from the INJ 31 and the anode gas injected from the auxiliary LS 32 into the ejector flow path 44. Therefore, the size of the ejector 4a is smaller than that of the ejector 4 including the large-diameter nozzle 41 and the small-diameter nozzle 42.

(Comparative example fuel cell system)
FIG. 8 is a configuration diagram showing a fuel cell system 100x of a comparative example. In FIG. 8, the same reference numerals are given to the configurations common to those in FIG. 1, and the description thereof will be omitted.

The fuel cell system 100x has ejectors 4j and 4k connected to INJ31 and auxiliary LS32, respectively, instead of the ejector 4. Each ejector 4j, 4k has a structure similar to that of the ejector 4a shown in FIG.

The outlet 46 of the ejectors 4j and 4k is connected to the inlet 11 of the FC1 via a bifurcated anode supply pipe L30x. Further, the inflow port 45 of the ejectors 4j and 4k is connected to the gas-liquid separator 5 via a bifurcated return pipe L33x.

When the INJ 31 injects the anode gas, the anode off gas is sucked from the gas-liquid separator 5 into the ejector 4j from the inflow port 45 via the return pipe L33x, as indicated by the arrow R33j. The anode gas injected from the INJ 31 flows through the ejector flow path 44 together with the anode off gas sucked from the inflow port 45, and is discharged from the outflow port 46 to the anode supply pipe L30x.

When the auxiliary LS32 and INJ31 inject the anode gas, the anode off gas is sucked from the gas-liquid separator 5 into the ejector 4k from the inflow port 45 via the return pipe L33x, as indicated by the arrow R33k. The anode gas injected from the INJ 31 flows through the ejector flow path 44 together with the anode off gas sucked from the inflow port 45, and is discharged from the outflow port 46 to the anode supply pipe L30x.

The ECU 70 warms up the FC1 by continuously executing the injection of the bypass LS33 and the auxiliary LS32. At this time, the anode gas injected from the bypass LS33 flows back to the ejectors 4j and 4k as indicated by the arrow R30r.

The ECU 70 executes the injection of the auxiliary LS 32 so that the backflow of the anode gas is suppressed. Therefore, the anode gas injected from the bypass LS33 flows to the inlet 11 of the FC1 as indicated by the arrow R30f.

At this time, the anode off-gas flows into the ejector 4k from the inflow port 45. Therefore, when the ECU 70 stops the injection of the auxiliary LS 32 when the warm-up operation is completed, the liquid water contained in the anode off gas remains in the ejector flow path 44 of the ejector 4k.

After the warm-up operation is completed, the ECU 70 intermittently executes the injection of the INJ 31 to perform the normal operation of the FC1. At this time, the anode off-gas flows into the ejector 4j from the inflow port 45 to generate liquid water in the ejector flow path 44, but since the injection of INJ31 is intermittently executed, the pressure of the anode gas pulsates. The liquid water in the ejector flow path 44 is easily discharged from the outlet 46.

In this example, since the ejector 4j connected to the INJ31 and the ejector 4k connected to the auxiliary LS32 are separate, liquid water remains in the ejector 4k after the injection of the auxiliary LS32 is stopped. Even if the injection of the auxiliary LS 32 is continued in the normal operation, the injection is continuously performed, so that the pressure pulsation of the anode gas does not occur unlike the INJ31. Therefore, it is difficult to discharge the liquid water in the ejector 4k.

On the other hand, the fuel cell systems 100 and 100a described above are provided with common ejectors 4 and 4a connected to the INJ 31 and the auxiliary LS 32. The ECU 70 continuously executes the injection of the auxiliary LS 32 during the warm-up operation, but intermittently executes the injection of the INJ 31 after the warm-up operation. Therefore, unlike the comparative example, the liquid water in the ejectors 4 and 4a is easily discharged by the pulsation of the pressure of the anode gas due to the injection of INJ31.

As described above, the ECU 70 warms up the FC1 by executing the injection of the bypass LS33, and injects the auxiliary LS32 so as to suppress the backflow of the anode gas from the bypass LS33 to the ejectors 4 and 4a. Execute. Since the auxiliary LS32 and the bypass LS33 continuously inject the anode gas, the backflow of the reaction gas to the ejectors 4 and 4a is suppressed, and the bypass LS33 to the FC1 have a high concentration that does not contain the impurity gas in the ejectors 4 and 4a. Warm-up operation can be performed by continuously supplying the anode gas.

Further, the ECU 70 executes the injection of INJ31 after the warm-up operation of FC1 is completed. Since the INJ 31 intermittently injects the reaction gas and the FC1 uses the anode gas for power generation, the pressure in the ejectors 4 and 4a pulsates due to the intermittent injection of the FC1.

Further, the ejectors 4 and 4a include a common ejector flow path 44 for flowing the anode off gas discharged from the outlet 12 of FC1 and the anode gas injected from INJ31 and the auxiliary LS 32 to the outlet 46. Therefore, the liquid water generated in the ejector flow path 44 by the injection of the auxiliary LS 32 is discharged from the outflow port 46 by the pulsation of the pressure due to the intermittent injection of the INJ 31.

Therefore, the fuel cell systems 100 and 100a of this example can easily discharge the liquid water remaining in the ejectors 4 and 4a after the FC1 is warmed up.

The embodiments described above are examples of preferred embodiments of the present invention. However, the present invention is not limited to this, and various modifications can be made without departing from the gist of the present invention.

1 Fuel cell 4,4a, 4j, 4k Ejector 5 Gas-liquid separator 6 Anode discharge valve 11 Inlet 12 Outlet 31 Injector 32 Auxiliary linear solenoid valve 33 Bypass solenoid valve 41 Large diameter nozzle 41a Nozzle 42 Small diameter nozzle 45 Inflow port 46 Outlet 70 ECU
73 Temperature sensor 100,100a Fuel cell system L30, L30x Anode supply pipe L32 Anode discharge pipe L33, L33x Return pipe L34 Bypass pipe

Claims (8)

A fuel cell equipped with an inlet and an outlet for the reaction gas used for power generation,
A first injection device that intermittently injects the reaction gas,
A second injection device and a third injection device that continuously inject the reaction gas,
An ejector provided with a discharge port for discharging the reaction gas discharged from the discharge port together with the reaction gas injected from the first injection device or the second injection device.
A first flow path connecting the introduction port and the discharge port,
A second flow path that guides the reaction gas injected from the third injection device to the first flow path without passing through the ejector, and
It has a first injection device, a second injection device, and a control device that controls injection of the third injection device.
The ejector includes a common third flow path for flowing the reaction gas discharged from the discharge port and the reaction gas injected from the first injection device and the second injection device to the discharge port.
The control device warms up the fuel cell by executing the injection of the third injection device, and the second flow path from the third injection device by executing the injection of the second injection device. And, after suppressing the backflow of the reaction gas from the discharge port to the third flow path through the first flow path and completing the warm-up operation of the fuel cell, the injection of the first injection device is executed. A fuel cell system characterized by The fuel cell system according to claim 1, wherein the control device stops the injection of the second injection device and the third injection device after the warm-up operation of the fuel cell is completed. The fuel cell system according to claim 1 or 2, wherein the control device stops the injection of the first injection device until the warm-up operation of the fuel cell is completed. The control device according to any one of claims 1 to 3, wherein the control device executes injection of the second injection device at a flow rate corresponding to the temperature of the fuel cell at the start of warm-up operation of the fuel cell. The described fuel cell system. The ejector injects the reaction gas injected from the first injection device into the third flow path, and the reaction gas injected from the second injection device into the third flow path. The fuel cell system according to any one of claims 1 to 4, further comprising a second nozzle. The ejector is characterized by having a common third nozzle that injects the reaction gas injected from the first injection device and the reaction gas injected from the second injection device into the third flow path. The fuel cell system according to any one of claims 1 to 4. The fuel cell system according to any one of claims 1 to 6, wherein the control device warms up the fuel cell until the temperature of the fuel cell exceeds the freezing point. The first injection device includes an injector.
The fuel cell system according to any one of claims 1 to 7, wherein the second injection device and the third injection device include a linear solenoid valve.

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